- wrap mappedaddr block by #ifdef INET for IPv6-only kernel in future. - rejects IPv6 packet toward IPv4-mapped address if its source address   is not an IPv4-mapped IPv6 address, since the converted IPv4 packets   would have an unexpected IPv4 source address. - when V6ONLY socket option is set, discard packets destined to a   v4/ipv4 mapped ipv6 address. - have PULLDOWN_TEST codepath. - get rid of in6_mcmatch().
- wrap mappedaddr block by #ifdef INET for IPv6-only kernel in future.
- rejects IPv6 packet toward IPv4-mapped address if its source address
  is not an IPv4-mapped IPv6 address, since the converted IPv4 packets
  would have an unexpected IPv4 source address.
- when V6ONLY socket option is set, discard packets destined to a
  v4/ipv4 mapped ipv6 address.
- have PULLDOWN_TEST codepath.
- get rid of in6_mcmatch().

Obtained from:	KAME

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase